Modular Reduction Using Special Modulus Forms

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Solution Overview

Problem

Cryptographic processes are vulnerable to side-channel attacks, such as power and electromagnetic analysis, which exploit information leaked during operations like decryption and signature generation, and conventional countermeasures like inserting dummy operations can slow down the process unacceptably.

Innovation Solution

The use of a modified Barrett reduction method with a special form of the modulus to speed up cryptographic processes by pre-computing static values and simplifying calculations, making it difficult for hackers to analyze secret keying material through changes in modular arithmetic patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional countermeasures like inserting dummy operations are used to prevent side-channel attacks, then security is improved, but computation speed deteriorates

Engineering Contradiction:
ImprovesecurityVSAvoidcomputation speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent changes the parameter of the modulus to a special form (where the modulus is of the form 2^k - 1 or similar specialized structure) to enable faster modular reduction operations. This parameter change allows the system to maintain security against side-channel attacks while significantly improving computation speed through optimized arithmetic operations.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces conventional modular reduction mechanisms (which require division operations) with a specialized Barrett reduction method that uses multiplication and bit shifting operations. This substitution of the computational mechanism enables faster execution while maintaining security properties.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If Barrett reduction method is used to reduce a single number, then division operations are eliminated, but computation time increases compared to divide algorithm

Engineering Contradiction:
Improvereduction method complexityVSAvoidcomputation time
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The patent pre-computes static values (such as the Barrett constant or modulus inverse) before performing the actual modular reduction operations. This preliminary action allows the subsequent reduction operations to be performed much faster using pre-computed data, eliminating the need for expensive division operations during the main computational process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent modifies the modulus parameter to a special form that enables more efficient Barrett reduction. By changing the modulus to a specialized structure (such as 2^k - 1), the reduction operation becomes significantly faster while maintaining the necessary cryptographic properties.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If modular arithmetic patterns are made more complex to mask secret key information, then security is improved, but computation efficiency deteriorates

Engineering Contradiction:
ImprovesecurityVSAvoidcomputation efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent changes the modulus parameter to a special form that creates a more complex modular arithmetic pattern. This parameter change masks secret key information from side-channel analysis while the specialized structure actually improves computation efficiency through faster reduction operations.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary Barrett constant or pre-computed value that mediates between the security requirement (masking secret keys) and the performance requirement (fast computation). This intermediary element enables both security and efficiency to coexist.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS8233615B2Modular reduction using a special form of the modulus
Publication Date: 2012.07.31 CRYPTOGRAPHY RESEARCH INC
  • US8233615B2 patent drawing
  • US8233615B2 patent drawing
  • US8233615B2 patent drawing

AI summary

A special form of a modulus and a modified Barrett reduction method are used to perform modular arithmetic in a cryptographic system. The modified Barrett reduction is a method of reducing a number modulo another number without the use of any division. By pre-computing static values used in the Barrett reduction method and by using a special form of the modulus, the calculation of reducing a number modulo another number can be reduced. This can result in a decrease in computation time, speeding up the overall cryptographic process.